Heroin overdose is the leading cause of premature mortality among heroin users (Smyth et al., 2007), and is the second most common drug responsible for poisoning deaths in New York City. Although deaths due to unintentional drug overdose decreased overall by 24% in NYC between 2005 and 2009, prescription opioid deaths increased by 20% during this same time period (Epi Data Brief, New York City Department of Health and Mental Hygiene (NYC DOHMH), 2011). A new harm reduction approach attempts to decrease opioid overdose by educating users in recognizing its symptoms and in using naloxone to reverse opioid-induced respiratory depression. In the proposed studies, we will attempt to obtain data on the impact that these programs may have on the health and outcomes of a population of opioid users at high risk for witnessing and experiencing an opioid overdose. We have preliminary evidence supporting the need for modifications of existing training programs to improve accurate identification of opioid overdose. Furthermore, a review of the literature has revealed that more extensive research, including proactive, long-term follow-up, is needed to better identify all of the benefits and risks associated with this approach. Specifically our investigation will recruit ongoing and recently detoxified opioid abusers from several sites throughout the NYC area. All participants will receive standard opioid overdose education training and naloxone to carry should they witness another person experiencing an overdose, or overdose themselves. One-third of the participants will be randomized to receive additional in-depth psychosocial education focusing on recognition and prevention of opioid overdose, and appropriate use of naloxone. Another one-third of the participants will receive the extensive training and be required to engage a spouse, partner, relative, or friend in this supplementary intervention. We expect that these psychosocial interventions (extensive training and training of a significant other) will improve overdose outcome measures. We also expect that the occurrence of naloxone-related adverse events will be minimal, and that access to naloxone will not significantly alter drug use patterns. The results of this study should provide one of the firs prospective and systematic assessments of the risks and benefits of this novel practice in the U.S., and educate the field on how we may improve upon current practices. In addition to conducting a prospective study, we also propose to conduct a retrospective analysis of the overall impact of overdose education and training in the use of naloxone by examining data collected by the NYC DOHMH. Specifically, both fatal and non-fatal opioid overdose rates will be compared in neighborhoods with facilities that offer overdose prevention training and naloxone to those that do not. We anticipate that the prevalence of fatal opioid overdose will be significantly lower in neighborhoods where opioid overdose prevention training and naloxone are offered.